Whingey 4 year old!

Bit of a long post.......Please somebody give me some advise! I can't take much more of my 4 year old. She spends 90% of her days whining and moaning over absolutely anything and everything. And the smallest thing can make her cry for ages. She's very hard to settle. I've tried ignoring it and explaining I'm only gonna talk to her if she can talk to me properly, sending her to her room to calm down, taking away toys, shouting just makes her worse but it's hard not to when I can't hear myself talk over her. I've done reward charts but she looses interest quickly. And if that's not bad enough she still doesn't sleep through the night. I always take her back to her bed when she wakes as I don't want to get her into the habit of sleeping in my bed but she cried and shouts and then wakes the whole house. It's all so draining when I also have a 6 year old (who has never been like this) and a 4 month old baby and I don't know what to do next! Someone please help!